@article{CMH_1985__60_139998,
     author = {Kenneth S. Brown and Ross Geoghegan},
     title = {Cohomology with free coefficients of the fundamental group of a graph of groups.},
     journal = {Commentarii mathematici Helvetici},
     pages = {31--45},
     publisher = {mathdoc},
     volume = {60},
     year = {1985},
     zbl = {0584.20037},
     url = {http://geodesic.mathdoc.fr/item/CMH_1985__60_139998/}
}